1. Field of the Invention
The present invention relates to a liquid ejection head for ejecting liquid and a flexible wiring substrate used in the liquid ejection head.
2. Description of the Related Art
The configuration of an inkjet recording head, which is a typical liquid ejection head that ejects liquid, disclosed in U.S. Patent Application Publication No. 2010/0045744, is known.
In the inkjet recording head disclosed in U.S. Patent Application Publication No. 2010/0045744, a flexible wiring substrate is connected to a recording-element substrate, and electric signals and power for ejecting ink are supplied to the recording-element substrate via the flexible wiring substrate. Furthermore, an electrical contact substrate that receives electric signals from an external device is connected to an end of the flexible wiring substrate. Because the recording-element substrate and the electrical contact substrate are joined to different surfaces of the ink supply unit, as shown in FIG. 1 of U.S. Patent Application Publication No. 2010/0045744, the flexible wiring substrate (i.e., a wiring tape 16 in FIG. 2 of U.S. Patent Application Publication No. 2010/0045744) connecting the recording-element substrate and the electrical contact substrate has a bent portion.
Wiring lines, which are provided on the flexible wiring substrate disclosed in U.S. Patent Application Publication No. 2010/0045744 and electrically connect the recording-element substrate and the electrical contact substrate, are provided over the entire bent portion so as to extend over the ridge of the bent portion. Because the flexible wiring substrate includes a resin film, the bent portion tends to return to the original shape due to the reaction force of the film. In the area in which the wiring lines are provided over the bent portion of the flexible wiring substrate, it is easy to maintain the flexible wiring substrate in a bent state because of the plastic deformation of the wiring lines.
However, in some configurations, there is an area in which portions provided with no wiring lines are continuous at a bent portion of a flexible wiring substrate. In such a case, it is difficult to maintain the flexible wiring substrate in a bent state in the area of the bent portion in which no wiring lines are provided because of the reaction force of the film. Thus, the radius of curvature of the bent portion increases, and the bent portion may project outward from the ink supply unit. Furthermore, when the flexible wiring substrate is bonded to the body of the inkjet recording head, in an area in which portions provided with no wiring line are continuous, a reaction force that causes the bent portion to return to the original state from the bent state is large. Thus, the flexible wiring substrate may be separated and loosened from the inkjet recording head due to this reaction force. As a result, when the inkjet recording head is scanned, the flexible wiring substrate may touch components in the inkjet recording apparatus or a recording sheet, damaging them.